<!DOCTYPE HTML>
<html>

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <title>navigator</title>
  <script type="text/javascript">
    function validB() {
      var u_agent = navigator.userAgent;
      var B_name = "不是想用的主流浏览器!";
      if (u_agent.indexOf("Firefox") > -1) {
        B_name = "Firefox";
      } else if (u_agent.indexOf("Chrome") > -1) {
        B_name = "Chrome";
      } else if (u_agent.indexOf("MSIE") > -1 && u_agent.indexOf("Trident") > -1) {
        B_name = "IE(8-10)";
      }
      document.write("浏览器:" + B_name + "<br>");
      document.write("u_agent:" + u_agent + "<br>");
    }
  </script>
</head>

<body>
  <form>
    <input type="button" value="查看浏览器" onclick="validB()">
  </form>
</body>

</html>